== to know this source file or files controlling the header of the bp-default theme. ==
The responsive stylesheet enqueued in bp-default functions.php file controls how the navigation menus are rendered when viewing the site on tablets and mobiles
https://buddypress.trac.wordpress.org/browser/tags/1.5.5/bp-themes/bp-default/_inc/css/responsive.css
thank you for the response. but i want to know further, how do i safely remove the blue background in the header. i will love to build my custom menu items and header image.
thank you
== how do i safely remove the blue background in the header. ==
@idowu create a bp-default child theme, go to wp-admin Appearance > Header and upload your header image. That’s it. Then override stylesheets. https://codex.buddypress.org/theme-development/building-a-buddypress-child-theme/